Sources and preservation of organic matter in Plum Island salt marsh sediments (MA, USA): long-chain n-alkanes and stable carbon isotope compositions
Sources and preservation of organic matter in Plum Island salt marsh sediments (MA, USA): long-chain n-alkanes and stable carbon isotope compositions
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DOI：
10.1016/j.ecss.2003.07.006
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发表时间：
2003-12
影响因子：
2.8
通讯作者：
Xuchen Wang;Robert F. Chen;A. Berry
中科院分区：
文献类型：
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作者：
Xuchen Wang;Robert F. Chen;A. Berry
测定了梅子岛盐沼中、上河口沉积物中互花米草、C4沼泽草、香蒲草、C3沼泽草和3个沉积物柱样的元素组成(TOC、TN、C/N)、稳定碳同位素(δ13C)组成和正构烷烃(nC16-38)含量。我们的结果表明，沉积物中保存的有机质受占采样点的沼泽植物的影响很大。表层淡水区沉积物中有机质的δ13C值受C3植物的影响较大(−2 3.0±0.3‰)，而中部沉积物(−18.9±0.8‰)和滩涂沉积物中的有机质(−19.4±0.1‰)主要受C4植物的影响。所有沉积物中正构烷烃的分布规律与沼泽草本植物互花米草和宽叶草中的分布规律相似，nC21~nC33长链正构烷烃是所有沉积物样品中检测到的主要化合物。在三种沉积物中都发现了强烈的奇偶碳数正构烷烃优势，其中nC29是所有样品中含量最丰富的同系物。这些沉积物中有机质的δ~(13)C组成和正构烷烃分布都表明，沼泽植物对梅花岛盐沼沉积物中保存的有机质具有重要的贡献。这表明盐沼在河口和邻近沿海水域的营养物质和有机碳的循环中起着重要作用。
Elemental (TOC, TN, C/N) and stable carbon isotopic (δ13C) compositions and n-alkane (nC16–38) concentrations were measured for Spartina alterniflora, a C4marsh grass, Typha latifolia, a C3marsh grass, and three sediment cores collected from middle and upper estuarine sites from the Plum Island salt marshes. Our results indicated that the organic matter preserved in the sediments was highly affected by the marsh plants that dominated the sampling sites. δ13C values of organic matter preserved in the upper fresh water site sediment were more negative (−23.0±0.3‰ ) as affected by the C3plants than the values of organic matter preserved in the sediments of middle (−18.9±0.8‰ ) and mud flat sites (−19.4±0.1‰ ) as influenced mainly by the C4marsh plants. The distribution of n-alkanes measured in all sediments showed similar patterns as those determined in the marsh grasses S. alterniflora and T. latifolia, and nC21to nC33long-chain n-alkanes were the major compounds determined in all sediment samples. The strong odd-to-even carbon numbered n-alkane predominance was found in all three sediments and nC29was the most abundant homologue in all samples measured. Both δ13C compositions of organic matter and n-alkane distributions in these sediments indicate that the marsh plants could contribute significant amount of organic matter preserved in Plum Island salt marsh sediments. This suggests that salt marshes play an important role in the cycling of nutrients and organic carbon in the estuary and adjacent coastal waters.